Understanding the processes in hemoprotein denaturation become a very important factor for production of blood substitutes based on extracellular hemoglobin. Clinical studies with different blood substitutes have reviled symptoms which are due to accelerated autoxidation and hemin dissociation. Autoxidation of the heme produces aquamethemoglobin (Hb+(H20)) in which the proximal His-Fe bond is much weakened. This allows heme dissociation and enhance protein unfolding. We are utilizing ultrafast time-resolved fluorescence of excited tryptophan decay together with the Forster model of radiationless excitation energy transfer between tryptophan and heme for monitoring the events in hemoprotein denaturation pathway. Our study include native myoglobins and hemoglobins as well as chemically modified (cross-linked between ` or ~ subunits) hemoglobin.